1. Field of the Invention
The present invention relates to night vision devices. More particularly, the present invention relates to night vision devices of the type which removably and relatively movably attach to a support structure secured to a face mask or to a helmet, for example, to thereby be supported in front of at least one eye of the user. As thus supported, the night vision device may be used by the wearer of the helmet or face mask to view a night scene while the user's hands remain free.
2. Related Technology
Conventional night vision devices are known which removably attach to a support structure secured to a helmet or face mask. These conventional night vision devices are relatively movable by manipulation of the support structure to align at least one eye piece of the night vision device with at least one eye of the user. Additionally, the support structure and night vision device are conventionally provided with cooperating structural features which insure that the night vision device is electrically deactivated when it is removed from the support structure. This conventional feature which turns off the night vision device when it is removed from the support structure prevents the battery pack of the device from being inadvertently run down by leaving the device on when it is not in use on the support structure. Also, this feature provides light security so that inadvertent light emissions do not occur.
A conventional night vision device which includes features turning off, or removing electrical power supply to, the night vision device when the latter is moved to a flipped up position is seen in U.S. Pat. No. 4,449,787, issued 22 May 1984, to James H. Burbo, et al. The teaching of the Burbo patent is believed to include the provision of a pair of recesses on a first part of the support structure attached to a helmet. A second part of the support structure is secured to the night vision device and includes a pair of pins receivable into the pair of recesses to pivotally attach and support the night vision device. Electrical contact between the night vision device and its battery pack is made through the engagement of the two parts of the support structure only when the night vision device is pivoted to its use position. Thus, when the night vision device is pivoted upwardly to allow the user unobstructed vision, power supply to the device is interrupted to save energy.
However, the support structure and electrical power interruption features of the Burbo device necessarily result in conduction of electrical power to the night vision device by way of electrical contacts which are exposed. In effect, these exposed contacts are switch contacts because they close and open in response to the pivotal movement of the night vision device between its use and flipped up positions. As a first consideration, such exposed electrical switch contacts are highly subject to damage which can interfere with the conduction of electrical power to the night vision device. Secondly, deterioration of the electrical switch contacts can result from environmental factors. That is, environmental factors may cause corrosion and other deterioration of such exposed contacts, including such undesirable effects as pitting, the formation of nonconductive oxide coatings, and the formation of other films or coatings on the exposed contacts. Of course, all of these environmental effects are detrimental to the reliable conduction of electrical power to the night vision device. The result is that such exposed electrical switch contacts compromise the service reliability of the night vision device, and cause the device to be frail instead of rugged and able to withstand the handling to which such devices are subjected in their use environment.
Another conventional night vision device is known in accord with U.S. Pat. No. 4,672,194, issued 9 Jun. 1987, to William A. Kastendieck, et al. This Kastendieck patent is believed to teach a night vision device which includes a head gear, and a night vision goggle. The goggle includes a power supply circuit having a magnetically-responsive switch in series with a bi-stable latching relay controlling power supply to the image intensifier tube of the goggle. This magnetically-responsive switch is arranged to remain closed, and to keep the power supply relay closed, so long as the switch is subjected to a sufficient magnetic flux. The head gear for the night vision device includes a permanent magnet disposed so that it is close to the magnetically-responsive switch when the goggle is on the head gear. When the goggle is removed from the head gear, the magnetically-responsive switch is moved away from the permanent magnet so that the switch opens, an electrical pulse moves the bi-stable relay to an open condition, and electrical power to the night vision goggle is interrupted. Thus, the goggle is prevented from inadvertently being left on when it is removed from the head gear and is not in use. Also, it is recognized that inadvertently leaving the night vision goggle on when it is not in use can attract the attention of hostile personnel to the phosphor green light emitted from the eyepieces of the goggle.
However, the night vision device according to the Kastendieck patent does not provide for the night vision goggle to be pivoted to a flipped up position while yet supported on the head gear. In order to obtain an unobstructed view with the unaided eyes, a user of the Kastendieck device must remove the night vision goggle from its position on the head gear in front of the user's eyes.